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[PATCH v1 3/7] Row pattern recognition patch (planner). 812+ messages / 2 participants [nested] [flat]
* [PATCH v1 3/7] Row pattern recognition patch (planner). @ 2023-06-25 11:48 Tatsuo Ishii <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Tatsuo Ishii @ 2023-06-25 11:48 UTC (permalink / raw) --- src/backend/optimizer/plan/createplan.c | 13 ++++++++++--- src/include/nodes/plannodes.h | 9 +++++++++ 2 files changed, 19 insertions(+), 3 deletions(-) diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c index 4bb38160b3..5ac65248a2 100644 --- a/src/backend/optimizer/plan/createplan.c +++ b/src/backend/optimizer/plan/createplan.c @@ -287,8 +287,8 @@ static WindowAgg *make_windowagg(List *tlist, Index winref, int frameOptions, Node *startOffset, Node *endOffset, Oid startInRangeFunc, Oid endInRangeFunc, Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst, - List *runCondition, List *qual, bool topWindow, - Plan *lefttree); + List *runCondition, List *patternVariable, List *patternRegexp, List *defineClause, + List *qual, bool topWindow, Plan *lefttree); static Group *make_group(List *tlist, List *qual, int numGroupCols, AttrNumber *grpColIdx, Oid *grpOperators, Oid *grpCollations, Plan *lefttree); @@ -2684,6 +2684,9 @@ create_windowagg_plan(PlannerInfo *root, WindowAggPath *best_path) wc->inRangeAsc, wc->inRangeNullsFirst, wc->runCondition, + wc->patternVariable, + wc->patternRegexp, + wc->defineClause, best_path->qual, best_path->topwindow, subplan); @@ -6581,7 +6584,8 @@ make_windowagg(List *tlist, Index winref, int frameOptions, Node *startOffset, Node *endOffset, Oid startInRangeFunc, Oid endInRangeFunc, Oid inRangeColl, bool inRangeAsc, bool inRangeNullsFirst, - List *runCondition, List *qual, bool topWindow, Plan *lefttree) + List *runCondition, List *patternVariable, List *patternRegexp, List *defineClause, + List *qual, bool topWindow, Plan *lefttree) { WindowAgg *node = makeNode(WindowAgg); Plan *plan = &node->plan; @@ -6607,6 +6611,9 @@ make_windowagg(List *tlist, Index winref, node->inRangeAsc = inRangeAsc; node->inRangeNullsFirst = inRangeNullsFirst; node->topWindow = topWindow; + node->patternVariable = patternVariable; + node->patternRegexp = patternRegexp; + node->defineClause = defineClause; plan->targetlist = tlist; plan->lefttree = lefttree; diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h index 1b787fe031..eb511176ac 100644 --- a/src/include/nodes/plannodes.h +++ b/src/include/nodes/plannodes.h @@ -1096,6 +1096,15 @@ typedef struct WindowAgg /* nulls sort first for in_range tests? */ bool inRangeNullsFirst; + /* Row Pattern Recognition PATTERN variable name (list of String) */ + List *patternVariable; + + /* Row Pattern Recognition PATTERN regular expression quantifier ('+' or ''. list of String) */ + List *patternRegexp; + + /* Row Pattern Recognition DEFINE clause (list of TargetEntry) */ + List *defineClause; + /* * false for all apart from the WindowAgg that's closest to the root of * the plan -- 2.25.1 ----Next_Part(Sun_Jun_25_21_05_09_2023_126)-- Content-Type: Text/X-Patch; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="v1-0004-Row-pattern-recognition-patch-executor.patch" ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
* [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table @ 2025-07-15 10:45 Jehan-Guillaume de Rorthais <[email protected]> 0 siblings, 0 replies; 812+ messages in thread From: Jehan-Guillaume de Rorthais @ 2025-07-15 10:45 UTC (permalink / raw) When a foreign table points to a partitioned table or an inheritance parent on the foreign server, a non-direct DML can affect multiple rows when only one row is intended to be affected. This happens because postgres_fdw uses only ctid to identify a row to work on. Though ctid uniquely identifies a row in a single table, in a partitioned table or in an inheritance hierarchy, there can be be multiple rows, in different partitions, with the same ctid. So DML statement sent to the foreign server by postgres_fdw ends up affecting more than one rows, only one of which is intended to be affected. This commit adds testcases to show the problem. A subsequent commit would have a fix to the problem. Author: Ashutosh Bapat <[email protected]> Reviewed-by: Kyotaro Horiguchi <[email protected]> Discussion: https://www.postgresql.org/message-id/flat/CAFjFpRfcgwsHRmpvoOK-GUQi-n8MgAS%2BOxcQo%3DaBDn1COywmcg%4... Rebased by Jehan-Guillaume de Rorthais <[email protected]> --- .../postgres_fdw/expected/postgres_fdw.out | 125 ++++++++++++++++++ contrib/postgres_fdw/sql/postgres_fdw.sql | 58 ++++++++ 2 files changed, 183 insertions(+) diff --git a/contrib/postgres_fdw/expected/postgres_fdw.out b/contrib/postgres_fdw/expected/postgres_fdw.out index 2185b42bb4f..62019eaa881 100644 --- a/contrib/postgres_fdw/expected/postgres_fdw.out +++ b/contrib/postgres_fdw/expected/postgres_fdw.out @@ -8954,6 +8954,131 @@ drop foreign table remt2; drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | aaa + fa | (0,1) | bbb +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; + QUERY PLAN +----------------------------------------------------------------------------------------------------------------- + Update on public.fa + Remote SQL: UPDATE public.a SET aa = $2 WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: CASE WHEN (random() <= '1'::double precision) THEN 'zzzz'::text ELSE NULL::text END, ctid, fa.* + Remote SQL: SELECT aa, ctid FROM public.a WHERE ((aa = 'aaa')) FOR UPDATE +(5 rows) + +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+------ + fa | (0,2) | zzzz + fa | (0,1) | bbb +(2 rows) + +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); + QUERY PLAN +--------------------------------------------------------------------------------------------------------------- + Delete on public.fa + Remote SQL: DELETE FROM public.a WHERE ctid = $1 + -> Foreign Scan on public.fa + Output: ctid + Filter: (fa.aa = CASE WHEN (random() <= '1'::double precision) THEN 'aaa'::text ELSE 'bbb'::text END) + Remote SQL: SELECT aa, ctid FROM public.a FOR UPDATE +(6 rows) + +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + tableoid | ctid | aa +----------+-------+----- + fa | (0,1) | bbb +(1 row) + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; +NOTICE: drop cascades to table b +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 1 | 1 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; + QUERY PLAN +------------------------------------------------------------------------------------------------- + Update on public.fplt + Remote SQL: UPDATE public.plt SET b = $2 WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: CASE WHEN (random() <= '1'::double precision) THEN 10 ELSE 20 END, ctid, fplt.* + Remote SQL: SELECT a, b, ctid FROM public.plt WHERE ((a = 1)) FOR UPDATE +(5 rows) + +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+---- + fplt | (0,2) | 1 | 10 + fplt | (0,1) | 2 | 2 +(2 rows) + +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); + QUERY PLAN +--------------------------------------------------------------------------------------------- + Delete on public.fplt + Remote SQL: DELETE FROM public.plt WHERE ctid = $1 + -> Foreign Scan on public.fplt + Output: ctid + Filter: (fplt.a = CASE WHEN (random() <= '1'::double precision) THEN 1 ELSE 10 END) + Remote SQL: SELECT a, ctid FROM public.plt FOR UPDATE +(6 rows) + +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + tableoid | ctid | a | b +----------+-------+---+--- + fplt | (0,1) | 2 | 2 +(1 row) + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== diff --git a/contrib/postgres_fdw/sql/postgres_fdw.sql b/contrib/postgres_fdw/sql/postgres_fdw.sql index e534b40de3c..ae3777b7edb 100644 --- a/contrib/postgres_fdw/sql/postgres_fdw.sql +++ b/contrib/postgres_fdw/sql/postgres_fdw.sql @@ -2494,6 +2494,64 @@ drop table loct1; drop table loct2; drop table parent; +-- test DML statement on a foreign table pointing to an inheritance hierarchy +-- on the remote server +CREATE TABLE a(aa TEXT); +ALTER TABLE a SET (autovacuum_enabled = 'false'); +CREATE TABLE b() INHERITS(a); +ALTER TABLE b SET (autovacuum_enabled = 'false'); +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +CREATE FOREIGN TABLE fa (aa TEXT) SERVER loopback OPTIONS (table_name 'a'); + +SELECT tableoid::regclass, ctid, * FROM fa; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +UPDATE fa SET aa = (CASE WHEN random() <= 1 THEN 'zzzz' ELSE NULL END) WHERE aa = 'aaa'; +SELECT tableoid::regclass, ctid, * FROM fa; +-- repopulate tables so that we have rows with same ctid +TRUNCATE a, b; +INSERT INTO a(aa) VALUES('aaa'); +INSERT INTO b(aa) VALUES('bbb'); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +DELETE FROM fa WHERE aa = (CASE WHEN random() <= 1 THEN 'aaa' ELSE 'bbb' END); +SELECT tableoid::regclass, ctid, * FROM fa; + +-- cleanup +DROP FOREIGN TABLE fa; +DROP TABLE a CASCADE; + +-- =================================================================== +-- test foreign table pointing to a remote partitioned table +-- =================================================================== + +-- test DML statement on foreign table pointing to a foreign partitioned table +CREATE TABLE plt (a int, b int) PARTITION BY LIST(a); +CREATE TABLE plt_p1 PARTITION OF plt FOR VALUES IN (1); +CREATE TABLE plt_p2 PARTITION OF plt FOR VALUES IN (2); +INSERT INTO plt VALUES (1, 1), (2, 2); +CREATE FOREIGN TABLE fplt (a int, b int) SERVER loopback OPTIONS (table_name 'plt'); +SELECT tableoid::regclass, ctid, * FROM fplt; +-- use random() so that DML statement is not pushed down to the foreign +-- server +EXPLAIN (VERBOSE, COSTS OFF) +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +UPDATE fplt SET b = (CASE WHEN random() <= 1 THEN 10 ELSE 20 END) WHERE a = 1; +SELECT tableoid::regclass, ctid, * FROM fplt; +-- repopulate partitioned table so that we have rows with same ctid +TRUNCATE plt; +INSERT INTO plt VALUES (1, 1), (2, 2); +EXPLAIN (VERBOSE, COSTS OFF) +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +DELETE FROM fplt WHERE a = (CASE WHEN random() <= 1 THEN 1 ELSE 10 END); +SELECT tableoid::regclass, ctid, * FROM fplt; + +DROP TABLE plt; +DROP FOREIGN TABLE fplt; + -- =================================================================== -- test tuple routing for foreign-table partitions -- =================================================================== -- 2.50.0 --MP_/4ZRYdF7Ah.pt5w65PuZdaPz Content-Type: text/x-patch Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=v3-0002-Error-out-if-one-iteration-of-non-direct-DML-affe.patch ^ permalink raw reply [nested|flat] 812+ messages in thread
end of thread, other threads:[~2025-07-15 10:45 UTC | newest] Thread overview: 812+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2023-06-25 11:48 [PATCH v1 3/7] Row pattern recognition patch (planner). Tatsuo Ishii <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]> 2025-07-15 10:45 [PATCH v3 1/2] Test exposing bug when foreign table points to a partitioned table Jehan-Guillaume de Rorthais <[email protected]>
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